1. Field of the Invention
The invention relates to a device for clamping flexible printing plates on the plate cylinder of rotary printing presses. Such a device can often be equipped with an apparatus for correcting the diagonal register of the printing plate by permitting a swivelling of the tensioning bars, wherein the ends of the plate can be clamped in the tensioning bars. Such correction apparatus can typically be provided in a recess of the plate cylinder.
2. Background Information
A known design of the type described above is provided in German Patent No. 15 36 954 C1. In this known device, both tensioning bars for the front and rear edges of the printing plate are adjustably held in slots by guide bolts. A lever which is swivellable about a pivot point and which, at its ends, engages both of the tensioning bars is provided for carrying out the adjustment. Through the intermediary of a work wheel and a worm wheel, the lever can be swivelled about a pivot point. As a result of the swivelling of the lever, the tensioning bars are moved in opposite directions and execute a swivelling motion through the intermediary of the slots and the guide bolts. The disadvantage of such a design is in the fact that there is a multiplicity of joints, with play-free motion not being possible in the long run, particularly in the slots for guiding the two tensioning bars.
Furthermore, with this known design, there is virtually no possibility, in the region of the printing plate, of a measuring point from which to determine the register error. That is, in the case of an adjustment to the diagonal register, it is also necessary to reset the circumferential and lateral registers, with this normally being checked by means of specimen prints. The known design, therefore, involves a complicated and time-consuming setting of the precise register.